Traditional hammers have a head with two functional ends, such as a strike face for striking nails into and a claw end for pulling nails out of a work piece, and the head is attached to a handle. Commonly, one end of the handle extends through an eye in the head, and a wedge is forced into the end of the handle to expand the handle end, holding it in place against the interior walls of the eye. Usually, the head is forged from steel, and the handle is wood. Such hammers have been in use for many years, and the manufacturing processes are well known.
Even in normal use, these hammers are subject to damage. One of the most common types of failure occurs when the handle fractures, splinters, or breaks just below the hammer head striking face. These failures typically occur when a user misses the intended nail or other target, hitting the target with the handle instead of the hammer strike face. In addition, the handle can be damaged if the claw is used to pull objects, and the objects scrape or impact the handle. Another type of damage occurs when the head chips or cracks during use, either due to impact with a target or due to manufacturing flaws in the steel or other metal. If the handle is damaged, it can be replaced by removing the wedge that secures it in the eye of the head, and installing a new handle and wedge. If the head is damaged, a new head can be installed on the existing handle. Generally the strike face of the hammer head is smooth, and it is common for a smooth head to slip off of the intended target if it is not directed toward the target with the striking force in exactly the correct direction.
One solution to the problem of damage to the hammer handle from overstriking and/or impacts with pulled objects is shown in FIG. 1. The head 10 is mounted to the handle 12 in the conventional manner, and metallic strips 14 are fastened to the handle 12 below the head 10 using screws 16. Another solution, shown in FIG. 2, provides another way to prevent damage to the handle. Head 20 includes a metallic plate or spine extending into a slot in handle 22, with protector 24 fitting against the outer surface of handle 22 and covering the slot. Fasteners 26 extend through handle 22 and the plate that extends into the slot in the handle.
Other hammers have been devised with the metallic head and handle forged or cast as a single piece, usually with a resilient textured grip around the end of the handle that is distal from the head to absorb shock and make the handle less slippery and easier for the user to hold onto. While this type of hammer is more resistant to damage from overstriking targets, its single-piece metal head/handle transmits more vibration and impact from the head to the user's hand, which tends to cause fatigue for the user. Thus, this type of hammer is generally not ideal for professional or other heavy duty use.
A more recent type of hammer is illustrated in FIG. 3. The hammer head 30 is forged or cast with a spine or neck 32 that extends into the handle 34. The head 30 includes claw 36 and an opening 38. A strike face 40 is fastened to the head 30, such as with a bolt 42 extending from opening 38 through a hole (not shown) in head 30 and into a threaded hole (not shown) extending into but not all the way through strike face 40. Strike face 40 can be easily replaced if it is damaged, such as by chipping during use.